How does a new hypothesis replace an order exclamation of something in the natural world

Calculate the number of molecules present in 0.750 mol of mgo.

Hey can you me with this i really need y’all

Consider the following multistep reaction: a b→ab(slow) a ab→a2b(fast)−−−−−−−−−−−−−−−−− 2a b→a2b(overall) based on this mechanism, determine the rate law for the overall reaction. express your answer in standard masteringchemistry format. for example, if the rate law is k[a]3[b]2 type k*[a]^3*[b]^2